APPLICATION OF THYRISTORS IN ENERGETICS AND THEIR OPTIMAL RC PROTECTION

Tiristori su osjetljivi na brzinu porasta anodnog napona, prenapona oporavka i brzinu porasta struje. Zbog toga se tiristori zaštićuju dodatnim sklopovima. Ponekad zaštitni sklop projektiran za prigušenje jednog prijelaznog procesa neće biti optimalan za prigušenje drugog procesa pa je nužno nekakvo kompromisno rješenje. U radu se analiziraju optimalni uvjeti rada zaštite tiristora, s tim da su u obzir uzeti parametri tiristora, koji su karakteristični za period uklapanja i isklapanja. Analiza je provedena u normiranom obliku, što analizi daje općenitost.Thyristors are susceptible to the increase rate of anode voltage, recovery overvoltage and current increase rate. They are therefore protected by means of supplementary circuits. Sometimes a protection circuit that has been designed to attenuate a certain transient process is not optimal for the attenuation of some other process, therefore a compromise solution is needed. In this paper, the optimal operating conditions of the thyristor protection are analyzed, where the thyristor parameters that are characteristic for the turn-on and turn-off period have been taken into consideration. The analysis has been performed in a normized form, which assures its general applicability

Porcelain veneers - preparation design: A retrospective review

This paper discusses the preparation of tooth design for porcelain veneers. It follows the literature more than three decades back in the past. From the very beginning, porcelain veneers were placed to no/minimally prepared tooth substance, showing different problems in clinical use. Later, the technique of etching the porcelain and controlling the reduction of tooth structure, presented the great steps forward in porcelain veneers accepting. A special accent concerning the preparative design was placed on variations of incisal edge preparation - the problem, which is still present in current practice. Additionally, the paper emphasizes the extremely demanding protocols in making the porcelain veneers as well as their expanded clinical indications

Novel Strategy for Electroanalytical Detection of Antipsychotic Drugs Chlorpromazine and Thioridazine; Possibilities for Simultaneous Determination

A simple and fast method for determination of two phenothiazine drugs, chlorpromazine (CPZ) and thioridazine (TDZ), at the boron-doped diamond electrode (BDDE) was proposed. Oxidation peaks on potentials higher than 1 V were used for quantitation of investigated phenothiazines due to better selectivity over common interfering compounds in urine. Differential pulse voltammetry was applied for trace determination of CPZ and TDZ, in Britton-Robinson buffer solution at optimal pH. Under optimized DPV conditions a linear analytical curve was obtained from 1.0x10(-7) to 4.0x10(-5) M with a detection limit of 0.3x10(-7) M (for CPZ) and in the concentration range of 2x10(-7) M to 4.0x10(-5) M, with a detection limit of 1.2x10(-7)M (for TDZ). The applicability of the method was proved by determination of CPZ and TDZ by proposed procedures in spiked urine samples. The electrochemical behavior of those two important tranquilizers in different solvents was described, exploring the possibility of simultaneous determination

Synthesis and characterization of LiFePo4/C cathode material by freeze drying method with PVP

Lithium iron phosphate is a promising cathode material for lithium ion battery application thanks to its good characteristics. Here is presented the freeze drying method for the preparation of carbon coated LiFePO4, where PVP is used as a carbon source. The main advantage of this method is mixing at the atomic level and introducing the carbon source into the precursor solution. The synthesis process can be divided into three stages: freezing of a precursor solution, drying under vacuum until water evaporates and calicination of as-dried powder at slightly reductive atmosphere. Powder X-ray diffraction measurement demonstrated single phase LiFePO4 with crystallite size of 45.8 nm. Morphology and particle size was revealed with scanning electron microscopy and particle size analyzer. Galvanostatic cycling from 2.3 to 4.1 V vs. Li/Li+, shows typical LiFePO4 redox behavior with plateau at 3.4 V. The discharge capacity value obtained at C/10 rate was 154 mAh- 1, with decrease on greater C-rates

Selective anticancer activity of hydroxyapatite/chitosan-poly(D,L)-lactide-co-glycolide particles loaded with an androstane-based cancer inhibitor

In an earlier study we demonstrated that hydroxyapatite nanoparticles coated with chitosan-poly(d,l)-lactide-co-glycolide (HAp/Ch-PLGA) target lungs following their intravenous injection into mice. In this study we utilize an emulsification process and freeze drying to load the composite HAp/Ch-PLGA particles with 17β-hydroxy-17α-picolyl-androst-5-en-3β-yl-acetate (A), a chemotherapeutic derivative of androstane and a novel compound with a selective anticancer activity against lung cancer cells. 1H NMR and 13C NMR techniques confirmed the intact structure of the derivative A following its entrapment within HAp/Ch-PLGA particles. The thermogravimetric and differential thermal analyses coupled with mass spectrometry were used to assess the thermal degradation products and properties of A-loaded HAp/Ch-PLGA. The loading efficiency, as indicated by the comparison of enthalpies of phase transitions in pure A and A-loaded HAp/Ch-PLGA, equaled 7.47 wt.%. The release of A from HAp/Ch-PLGA was sustained, neither exhibiting a burst release nor plateauing after three weeks. Atomic force microscopy and particle size distribution analyses were used to confirm that the particles were spherical with a uniform size distribution of d50 = 168 nm. In vitro cytotoxicity testing of A-loaded HAp/Ch-PLGA using MTT and trypan blue dye exclusion assays demonstrated that the particles were cytotoxic to the A549 human lung carcinoma cell line (46 ± 2%), while simultaneously preserving high viability (83 ± 3%) of regular MRC5 human lung fibroblasts and causing no harm to primary mouse lung fibroblasts. In conclusion, composite A-loaded HAp/Ch-PLGA particles could be seen as promising drug delivery platforms for selective cancer therapies, targeting malignant cells for destruction, while having a significantly lesser cytotoxic effect on the healthy cells.This is the peer-reviewed version of the articleIgnjatović, N.L., Penov-Gaši, K.M., Wu, V.M., Ajduković, J.J., Kojić, V.V., Vasiljević-Radović, D., Kuzmanović, M., Uskoković, V., Uskoković, D.P., 2016. Selective anticancer activity of hydroxyapatite/chitosan-poly(d,l)-lactide-co-glycolide particles loaded with an androstane-based cancer inhibitor. Colloids and Surfaces B: Biointerfaces 148, 629–639. [https://doi.org/10.1016/j.colsurfb.2016.09.041

On tensors of elasticity

An objective of this paper is to reconcile the "symmetry" approach with the "symmetry groups" approach as these two different points of view presently coexist in the literature. Here we will be concerned exclusively with linearly elastic materials. The starting point for an analysis of the inherent symmetry of elastic materials is the notion of a symmetry transformation. Particularly, we paid attention to the compliance tensor for cubic and hexagonal crystals

On anisotropic elasticity damage mechanics

The anisotropic elasticity damage mechanics is considered within the framework of the classical theory of elasticity. Starting from the principle of strain equivalence and notion of isotropic group, damage tensor components are derived in terms of elastic parameters of undamaged (virgin) material in closed-form solution. The procedure was applied for several symmetries that are important for applications

On the state of pure shear

Abstract The algebraic proof of the fundamental theorem concerning pure shear, by making use only of the notion of orthogonal projector, is presented. It has been shown that the state of pure shear is the same for all singular symmetric traceless tensors in E 3 , up to the rotation

On the state of pure shear

The algebraic proof of the fundamental theorem concerning pure shear, by making use only of the notion of orthogonal projector, is presented. It has been shown that the state of pure shear is the same for all singular symmetric traceless tensors in E3, up to the rotation

Micro-methods for genotypic screening of hazelnut (Corylus Avellana) seeds to accelerate breeding for seed metabolite improvement

The expression of the taste and aroma of the hazelnut seed is related to the content, amount, and relative proportion of metabolite components in the cotyledons. Therefore, for breeding purposes, it is desirable to detect those compounds at a single seed level and establish the possible association of the content of those compounds with the embryo genotype and with the alleles transmitted by the pollen, i.e. male parent. We used hazelnut full-sib (FS) seed progenies from controlled pollination for efficiency testing of a multi-micro-method procedure comprising: a generalized low reagent-cost and low amount of extracting-tissue protocol for DNA purification and SSR seed genotyping, nuclear magnetic resonance (NMR) detection of analyte spectra for phenotyping metabolite content, and in vitro culture for clonal propagation of the embryo genotype. NMR was extremely efficient to measure the amount of multiple primary and secondary cotyledonary metabolites; SSR-PCR produced neat and polymorphic DNA fragments for the tested primer set and in vitro culture gave each embryo a probability of 0.85 to germinate and to be cloned in 3-4 ramets through seedling micro-cutting propagation. These micro-methods and the results obtained by their application are now available to be integrated into breeding programs for hazelnut fruit metabolite improvement